Preheat oven to 350 degrees. Butter a 9-inch tube pan with a removable bottom or a 9-inch spring form pan with a small, tall, round oven-safe ramekin in the center (grease it well).
In a medium bowl whisk together the flour, baking powder, baking soda and 1/2 teaspoon salt.
In a separate large mixing bowl or in the bowl of a stand mixer beat butter and sugar together on medium speed until pale and fluffy 2 – 3 minutes. Beat in eggs one at a time, then the vanilla.
Beat in the flour mixture in three additions, alternating with the sour cream and beginning and ending with the flour. Continue to beat until well combined.
Spoon half the batter into the pan. Sprinkle the filling evenly over the batter. Drop spoonfuls of the remaining batter over the top and gently spread them evenly over the filling.
Sprinkle the crumb topping evenly over batter.
Bake until the cake is golden brown and a toothpick inserted into the center comes out clean, about 55 minutes. Transfer to a wire rack to cool completely.
Remove the cake from the pan and place on a cake dish or platter.